The present invention relates to an improved alkaline battery using manganese dioxide and nickel oxyhydroxide as positive electrode active material.
Alkaline batteries, for example, alkaline dry batteries, have a structure in that a cylindrical positive electrode is closely fitted in a positive electrode casing, which also functions as a positive electrode terminal, and a gel negative electrode is disposed on the center of the cylindrical positive electrode via a separator.
The equipment using these batteries has increased loading, so that batteries having excellent heavy-loading discharge characteristics have been demanded.
One proposed technique mixes nickel oxyhydroxide with a positive electrode material mixture, which constitutes the positive electrode, to provide a battery having excellent heavy-loading discharge characteristics (for example, JAPANESE LAID-OPEN PATENT PUBLICATION Sho 57-7226m6).
The proposed alkaline battery including manganese dioxide, and nickel oxyhydroxide as the positive electrode active material has poor storage performance and large self discharge especially when being stored at high temperatures, compared with the conventional alkaline dry battery without nickel oxyhydroxide. After the long-term storage, such proposed alkaline battery with nickel oxyhydroxide has poorer heavy-loading discharge characteristics than the alkaline dry battery without nickel oxyhydroxide.
The object of the present invention is thus to provide an improved alkaline battery that can maintain the good heavy-loading discharge characteristics even after the long-term storage at high temperatures.
The present invention is directed to an alkaline battery comprising a positive electrode containing manganese dioxide and nickel oxyhydroxide as an active material, a negative electrode containing zinc as an active material, and an alkaline electrolyte, wherein the positive electrode further contains at least one compound selected from the group consisting of an oxygen-containing zinc compound, an oxygen-containing calcium compound, an oxygen-containing yttrium compound, and an oxygen-containing titanium compound.
It is preferable that the content of the oxygen-containing compound is 0.1 to 10% by mole of nickel oxyhydroxide contained in the positive electrode.
It is also preferable that the oxygen-containing zinc compound is zinc oxide or zinc hydroxide, the oxygen-containing calcium compound is calcium oxide or calcium hydroxide, the oxygen-containing yttrium compound is yttrium oxide or yttrium hydroxide, and the oxygen-containing titanium compound is titanium dioxide.
It is further preferable that the positive electrode contains 20 to 90% by weight of manganese dioxide and 80 to 10% by weight of nickel oxyhydroxide.